distribute	reads
0-500	4950
500-800	3064
800-1000	2136
1000-1200	2573
1200-1400	3229
1400-1600	4671
1600-1800	7275
1800-2000	11669
2000-2200	17974
2200-2400	24681
2400-2600	31743
2600-2800	37183
2800-3000	40600
>3000	209457
